This invention relates to a process for preparation of chlorinated polyolefin resins in a reaction medium which is resistant to chlorination.
Chlorinated olefin polymers are well-known and widely available compositions which find use as general purpose elastomers, adhesives, and coating compositions. The polymers provide excellent resistance to acids, bases, and solvents, and, in addition, they display a high degree of flexibility, ozone resistance, and general overall weatherability. Substantial quantities of these produces are fabricated into pond and pit liners, roofing membranes, binder resins for coatings, gaskets, wire coverings, and adhesives.
The polymers are prepared on a commercial scale by solution or suspension chlorination olefin homopolymers or copolymers in a chlorinated reaction medium, such as carbon tetrachloride, chloroform, methylene chloride, or trichlorofluoromethane. When a solvent process is used the preferred medium is carbon tetrachloride because it is totally inert to chlorination, it is readily available, and it is easily separated from the polymer product. The use of carbon tetrachloride has been increasingly restricted however due to its activity as a stratospheric ozone depleter and the fact that it is a suspected human carcinogen. Consequently there is a need in the art for a solvent which can be used in chlorination reactions on a commercial scale which combines the desirable features of carbon tetrachloride without its disadvantages.